ON PRUNING. 
H3 
methods to prove inefFedlual : Nor will the application of 
either pitch, bees wax, or fealing wax, (at the fame time fearing 
the wounded part with a hot iron) anfwer the intended pur- 
pofe. 
When 
“ vacuo, and animals die when deprived of air. It has two Hates, being 
“ either elaftic or fixed. Dr. Hales obferves, that, in its elaftic and adlive 
“ Hate, it conduces to the invigorating the juices of vegetables ; and, in its 
“ fixed and inert Hate, gives union, weight, and firmnefs to all natural 
“ bodies. By his experiments we are informed, that fixed air conftitutes 
“ near one third part of the folid contents of the heart of oak. It is found to 
bear the fame proportion in peafe, beans, and other vegetable fubflances. 
“ Heat and fermentation render it elaftic. It is again capable of being ab- 
“ forbed and fixed. Was the whole air of the univerfe brought at once into 
“ an elaftic and repulfive ftate, every thing would fufFer a fudden diflblution. 
“ Was it entirely fixed, then all things would be reduced to an inert lump. 
“ Almighty providence has provided againft thefe extremes, and in the moft 
“ wonderful manner preferves the balance. Air is to be found in every por- 
« tion of earth ; and as it always contains a folution of the volatile parts of 
“ animal and vegetable fubftances, we ftiould be careful to keep our ftiff foils 
“ as open as poffible to its influence. It pafles, both in its adive and fixed 
“ ftate, into the abforbent velTels of the root, and mixing with the juices of 
« the plant, circulates through every part. Dr. Hales, in his Statical Experi- 
“ ments upon the Vine, difcovered it afcending with the fap in the bleeding 
“ feafon. 
“ Having demonftrated, that the motion of the fap depends upon the influence 
“ of the air, and the power of abforption common to all capillary tubes, it na- 
“ turally follows that it cannot remain one moment at reft. The gradations 
“ from heat to cold and vice verfa^ are infinite, and fometimes defultory. So 
“ muft the motion of the fap. From the combinations of the nutritive 
“ particles. 
